I don’t think the poster is backing Scriptures as forgeries. However, when we look at the absence of the original manuscripts outside the Catholic Church, it is very difficult (If not impossible) to understand the validity of Scriptures by themselves, from a secular (Maybe even academic) point of view.
However, what I can gather (read “assume”

) is that the poster is happy and grateful for the Catholic Church continued presence since our Lord walked the earth in human form and that he left us with His disciples to establish His Church.
Without the Church, people would be left with a collection of scrolls and wild guesses as to what is and isn’t Scripture. The Gospel of Thomas, The Shepherd of Hermas, and who knows what other books would be considered Scriptures.
If we take away the Catholic Church and Its Councils we would have no idea. No matter how much some people want to deny it and how many “what if’s”,
it is what it is.
It was through the Church that we learned what is Scriptures.